PSI - Issue 44

Fabrizio Paolacci et al. / Procedia Structural Integrity 44 (2023) 307–314 Fabrizio Paolacci et al. / Structural Integrity Procedia 00 (2022) 000–000

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5. Conclusions

The present paper proposed a novel algorithm for natural record selection to be employed for seismic risk assessment of structures. It based on the idea to control the response variability evaluating the seismic hazard curves without considering the randomness of GMPE, which instead is transferred to the fragility curves. For this purpose, the hazard curves were calculated assuming the factor, which measures the randomness of the GMPE, as deterministic. The fragility curves are built by using groups of accelerograms, whose median and 84% fractile spectra fit well the uniform hazard spectra for = 0 and 1, respectively. In this respect, a new search algorithm for selecting natural records was proposed and implemented in the Matlab script Scores. The main advantages of the proposed method are at least two: a) it is no longer necessary to refer to a specific , but only requiring spectrum compatibility conditions of the ground motion records with mean and mean+standard deviation UHS. b) it allows the selection of pairs of spectrum-compatible natural records, solving the problem of the seismic assessment of three-dimensional structure. The method has been applied to a 4-floors three-dimensional reinforced concrete frame structure. The case study, even though simple, was sufficient to investigate all the peculiarities of the proposed framework for risk assessment of structures, that is: i) the independence of the fragility curves from the set of the accelerogram used, ii) the method employs unscaled or lightly scaled accelerograms. This allows to mitigate the distortion of the seismic signals due to the application of extremely high scale factors, typically used in seismic risk assessment, iii) the number of records used for the application is in line with the minimum number of accelerograms suggested in the literature. Further developments could concern the application of the method to other types of structures, like steel structures or high-rise buildings, typically more flexible and for which the presence of higher vibration periods could represent a limitation. Acknowledgements The research leading to these results has received funding from the Italian Ministry of Education, University and Research (MIUR) in the frame of the "Departments of Excellence" (grant L 232/ 2016). References Alavi B, Krawinkler H. Behavior of moment-resisting frame structures subjected to near-fault ground motions. Earthquake Eng. Struct. Dyn. 2004; 33(6): 687–706. Baker JW. Efficient analytical fragility function fitting using dynamic structural analysis. Earthquake Spectra 2015; 31(1): 579-599. Baker J. Probabilistic structural response assessment using vector-valued intensity measures. 2007; 36(13): 1861-1883 Cornell CA. Calculating Building Seismic Performance Reliability: A Basis for Multi-Level Design Norms. 11 WCEE. Eleventh World Conference on Earthquake Engineering. Paper No. 2122. Acapulco, Mexico, June 23-28, 1996. 1996 Lin T, Haselton CB, Baker JW. Conditional-Spectrum-based ground motion selection. Part I: Hazard consistency for risk based assessments. Earthquake Engineering Structural Dynamics, 2013, 42: 1847-1865. Masi A, Chiauzzi L, Santarsiero G, et a. Seismic response of RC buildings during the Mw 6.0 August 24, 2016 Central Italy earthquake: the Amatrice case study. Bulletin of Earthquake Engineering 2019; 17: 5631–5654. Mackie K, Stojadinovic B. Comparison of Incremental Dynamic, Cloud, and Stripe Methods for Computing Probabilistic Seismic Demand Models. Structure Congress 2005. Paolacci F, Giannini R., Alessandri S., De Felice G., (2014), Seismic vulnerability assessment of a High Voltage Disconnect Switch, Soil Dynamics and Earthquake Engineering. Vol. 67, pp. 198-207, DOI: 10.1016/j.soildyn.2014.09.014 Paolacci F, Phan H.N., Corritore D., Alessandri S., Bursi O.S. , Reza M.S, (2015), Seismic Fragility Analysis Of Steel Storage Tanks, ECCOMAS Thematic Conference - 5th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering, COMPDYN 2015, 25 - 27 May 2015 Crete Island, Greece Phan HN, Paolacci F, Di Filippo R, Bursi OS. Seismic vulnerability of above-ground storage tanks with unanchored support conditions for Na-tech risks based on Gaussian process regression. Bull Earthquake Eng 2020; 18: 6883–6906. Shome N, Cornell CA, Bazzurro P, Carballo JE. Earthquakes, records, and nonlinear responses. Earthquake Spectra 1998; 14(3): 469-500 Vamvatsikos D, Cornell CA. Developing efficient scalar and vector intensity measures for IDA capacity estimation by incorporating elastic spectral shape information. Earthquake Engineering & Structural Dynamics 2005; 34(13): 1573- 1600. doi: https://doi.org/10.1002/eqe.496